Habit and structure. Thallus dark green, very firm, more-or-less globose, to 12 cm in diameter, becoming hollow by breakdown of central medullary filaments, very firmly attached by a mass of rhizoids. Utricles in large clusters, (70–)90–125(–180) µm in diameter at apex, then slightly constricted and expanding below to 200 µm in diameter, then gradually tapering, 1–3 mm long; utricles near base of thallus to 280 µm in diameter; utricle apices symmetrically rounded, wall very slightly to moderately (–30 µm) thickened, lamellate with a slight introrse umbo; hairs absent but wall scars common. Medullary filaments tapering evenly from lower part of utricles, becoming 30–40 µm in diameter.
Reproduction. Gametangia elongate-ovoid to cylindrical, 50–95 µm in diameter, 400–500 µm long.
Distribution. From Middle I., Recherche Arch., W. Aust., to Walkerville, Vic., and around Tas.
Habitat. Occurs from low tide level (where shaded) down to 20 m on rough-water coasts.
[After Womersley, Mar. Benthic Fl. Southern Australia I: 232 (1984)]